Column



Jan. 15, 1935.

e. B. COUBROUGH 1,988,188

COLUMN Filed July 13, 1932 Patented Jan. 15, 1935 COLUMN George B.Conbrough, Long Beach, Calif., ac-

signor to The Lummus Company, New York, N. Y., a corporation of DelawareApplication July 13, 1932, Serial No. 822,209

4 Claims.

The present invention relates to columns and more particularly todistilling and rectifying columns in which provision is made forobtaining v section for intermediate products is arranged in an annularspace adjacent the inside wall of the column, the center portion of thecolumn being used as a vapor passage. In such a column, the strippingsection takes up a large proportion of the cross-sectional area of thecolumn, thereby restricting the central vapor passage. The vapor passageis necessarily of relatively small crosssection and cannot be increasedbeyond a certain limit without restricting the stripping section to sucha narrow annular space that an unfavorable distribution of liquidresults. Moreover, the central vapor passage takes up space in thecolumn without serving any purpose other than a conduit.

The principal object of the present invention is to provide a columnhaving a stripping section so disposed as to provide ample space forpassage of the vapors and also to make-use of the vapor passage foraccommodating entrainment separators or the like. To this end, thepresent invention consists in the column hereinafter described andparticularly defined in the claims.

In the accompanying drawing, Fig. l is a diagrammatic elevation of thepreferred form of column; Fig. 2 is a section on line 2--2 of Fig. 1;and Fig. 3 is a section on line 3-3 of Fig. 1.

The preferred form of column, as shown in the drawing, comprises a shell4 having contact means arranged in several stages and illustrated as theboiling cap decks 6. Between stages of boiling cap decks is located anintermediate stripping column 8 which comprises a shell disposedcentrally of the main column. This stripping column is provided withboiling cap decks 10. The upper part of the shell 8 is joined to thelowermost deck of the rectifying stage immediately above.

Down pipes 12 are employed to convey reflux from deck to deck. Downpipes 14 are also employed to convey reflux downwardly into the centralstripping column. It will be noted that there is no passage for refluxliquid from the lowermost deck of any rectifying stage except into thestripping section. A down pipe 16 leads from the bottom of the strippingsection to the uppermost deck of the rectifying stage next below. Steamis admitted to the rectifying section through a pipe 18. A side productmay be withdrawn from the stripping column through a draw-ofl' 20 havinga valve 22. The opening of the valve 22 determines the amount of liquiddrawn off and hence determines the proportion returned to the rectifyingstage immediately below the stripping column.

The stripping column is internally supported from the shell 4 by meansof inclined struts 24 secured at their inner ends to the shell 8 and attheir outer ends upon annular ledges 26 attached to the inner wall ofthe main shell. These struts are used to support entrainment separatorswhich consist of a series of annular overlapping bailies 28. As shown inFig. 1, each baiile is mounted between adjacent struts, being supportedon angles 30 welded to the struts. At its outer edge, each baflle isformed with a hook-like lip 32 forming a trough to convey entrainmenttoward the struts. Beneath each strut is supported a channel member 34serving to convey entrainl'ltllellllt downwardly toward the wall of themain s e In operation of the column, the vapors pass through thelowermost rectifying stage and then around the central stripping columninto the rectifying stage next above. The vapors in their passagethrough any rectifying stage are contacted with downwardly flowingreflux which eventually passes into the central stripping column. Anyremnant of lighter materials present in the reflux is stripped therefromby steam introduced through the pipe 18, leaving in the bottom of thestripping column a material intermediate to the final vapors and themainresidue.

The vapors in their passage around the stripping section are deflectedoutwardly by the entrainment catching baflles. The change in thedirection of the vapors effectively throws off any entrainment, some ofwhich is caught in the troughs at the edges thereof. The entrainmentthus caught flows toward the struts and either runs down the struts ordrops into the channels 34 by which means it is carried to the insidewall of the main column. The entrainment falling down the inside wall istherefore not permitted to be carried upwardly again in the vaporstream.

By this construction, the entrainment separators are convenientlydisposed in the annular space surrounding the stripping column, whichspace would otherwise be of no value. The use of such entrainmentseparators permits a reduction in the number of decks required in anyrectifying stage, the decks being then used only for their intendedpurpose of rectification without being required to assume any of theduty of entrainment separation. Accordingly. by the elimination of someboiling cap decks, the cost of the material is greatly reducedparticularly since the overall height of the column may be no greaterthan that of an ordinary column without the stripping section.

The stripping column is necessarily of only small diameter since thequantity of vapors formed therein is small in comparison to the totalvapors passing through the main column. Accordingly, the annular spacesurrounding the stripping-column is sufllciently large to accommodatethe full volume of vapors. Since the decks in the stripping column areof regular circular shape, they present no problem of liquiddistribution. such as may occur with annular decks.

Having thus described the invention, what is claimed is:

l. The combination with a main column having contact means, of aninternal stripping column, means for supporting the stripping columnfrom the walls 01' the main column to provide an annular vapor passagearound the stripping column, and overlapping entrainment catching bamestraversing said passage.

2. The combination with a main column having contact means, 01' aninternal stripping column, means for supporting the stripping columnfrom the walls of the main column to provide an annular vapor passagearound the stripping column, including inclined struts, and annularoverlapping entrainment catching baflles on the struts.

3. The combination with a main column having contact means, of aninternal stripping column, means for supporting the stripping columnfrom the walls oi the main column to provide an annular vapor passagearound the stripping column, including struts inclined downwardly fromthe stripping column to the main column, annular overlapping entrainmentcatching baifles on the struts, and a channel below each strut to conveyentrainment to the walls of the main column.

4. The combination with a main column having contact means, of aninternal stripping column, means for supporting the stripping columnfrom the walls of the main column to provide an annular vapor passagearound the stripping column including struts inclined downwardly fromthe stripping column to the main column, and annular overlappingentrainment catching plates on the struts, each plate having an outerlip to convey entrainment to the struts, along which it passes to thewall of the main column.

GEORGE B. COUBROUGH.

